The present invention relates to a new solid sodium perborate which is particularly rich in active oxygen. It also relates to a process for its manufacture and use as a bleaching agent.
The majority of processes for the production of super-oxidized sodium perborate involve drying beyond the monohydrate phase and give effervescent products which release molecular oxygen as soon as they come into contact with water, but have a low active oxygen content as determined by titration with permanganate.
It has, however, been possible to produce super-oxidized perborate with a high active oxygen content by the direct reaction of excess hydrogen peroxide with a borate in an aqueous medium, as disclosed in British Pat. No. 798,217 filed on Oct. 21, 1955 by Henkel and Cie. GmbH, or in an organic medium as disclosed in French Pat. No. 1,590,710 filed on Sept. 30, 1968, by Sandoz S. A. However, these products appear to owe their high active oxygen content to the presence of hydrogen peroxide which is occluded in the solid substance. Consequently, they have a low resistance to abrasion. Moreover, these products contain two hydrogen atoms per active oxygen atom.